This project continues development of a trend theory to explain drug use trends with research based in the Baltimore metropolitan area. Two cases have been analyzed to date, current experimentation with heroin among suburban youth, and the epidemic of heroin use among African-Americans in the nineteen-sixties. Preliminary models have been developed, drawing on work in complexity theory, to account for feedback loops among populations and distribution systems such that heroin epidemics emerge. Methodology draws on numerous sources, including ethnographic interviews and oral histories, library and university archives, media outlets, institution-produced records, and popular and professional literature. Data are analyzed using abductive research processes similar to those described in the literature on grounded theory. This project continues the work in two major ways. First, research will continue with suburban youth, extending the focus to include any illicit drug. Trend theory will be used to make forecasts of drug use trends and then test those forecasts. Furthermore, theory-based forecasts will be integrated with youth program processes. Second, research will expand to investigate all illicit drug use trends in the Baltimore area from World War II until the present. The variety of drug trends will allow a test of the theory against several different populations and substances against changing historical conditions.